Wheat farmers offset climate change impact with technology… but for how long?

Technological advances have enabled Australian wheat farmers to offset the effects of climate change in the past 25 years; however, a reduction in yield potential over that time indicates a future risk to the $5 billion industry, CSIRO research has found.

Australia’s average wheat yields, which more than tripled between 1900 and 1990, did not increase from 1990 to 2015. The research found that during this 25-year period, the nation’s yield potential actually declined by 27%.

CSIRO team leader Dr Zvi Hochman said the study found that Australia’s wheat-growing zone had experienced an average rainfall decline of 2.8 mm or 28% per cropping season, and a maximum daily temperature increase of around 1°C from 1990 to 2015.

These observations are consistent with the higher end of future climate change projections for the wheat zone over the coming 26 years.

The findings, published in the journal Global Change Biology, indicate a risk to the future prosperity of Australia’s wheat industry, which contributes around 12% of the total wheat traded globally.

Dr Hochman said despite the adverse trend in growing conditions, wheat farmers have so far managed to maintain yields at 1990 levels of around 1.74 tonnes per hectare. He said this indicated wheat farmers were making the most of developments in farming technology; however, their best efforts were merely enabling them to keep pace with the impacts of a changing climate.

The study analysed 50 weather stations with the most complete records across Australia’s wheat-growing regions, spanning five states from the east to the west coast.

Wide annual variation in climate, yield potential and actual yields are normal in Australia; however, the probability of seeing the trends shown by this study across 50 weather stations over 26 years through random seasonal variability is less than one in 100 billion.

“Assuming the climate trends we have observed over the past 26 years continue at the same rate, even if farmers continue to improve their practices, it is likely that the national wheat yield will fall,” Dr Hochman said.

“We estimate that the recent average yield of 1.74 tonnes per hectare will fall to 1.55 tonnes per hectare by 2041.

“The 2016 season is expected to result in a bumper crop; however, our preliminary estimates show that yield potential in 2016 was about the same as in 2010. So, yield potential was high, but not exceptional.”

Although the study focused on wheat, the CSIRO said the findings would be broadly applicable to other cereal grains, pulses and oilseed crops, which grow in the same regions and same season as wheat.

Image caption: Dr Zvi Hochman. Credit: CSIRO